Just finished reading this yesterday! Someone said that that the book is an exploration of the question - "what is real art?". Hobie talks about how art means different things to different people. An art collector, a dealer, a person buying a book from a gift shop that has a reproduction of the piece etc. And how it would mean different things to different people, far into the future. That said, my takeaway was beyond the commentary on art. Theo may be an unreliable narrator but he talks about life is a catastrophe. And how he thinks everything he wants is an illusion but there's charm in wanting and experiencing that illusion. He also talks about how some secrets define who we are on the inside and that the painting helped him realize who he is. To me, the painting is Theo's way of learning and accepting who he is. >!There's a line in the last few pages that say "There is no resolution". Maybe Theo doesn't intend to end his narration in a conclusive way. In my view, the painting is yet another part of Theo's life that has touched him but he will never get to own. There is no resolution for Theo. No Pippa. No Kitsey (though he hinted that the engagement wasn't off?). No painting. Even Boris. Was there a conclusion or continuation of that relationship? !<IDK, maybe I read too much into those last few pages but that was my takeaway!
Also OP, as to why it won the Pulitzer - I'm not sure! Just like the painting, the book can mean different things to different people. As an exploration of someone coping with trauma and using art as a way to explore themes like loss, temptation, addiction, love, friendship and crime, its a good (without being spectacular) book Like most people, I liked the first 2/3 of the book and the last act felt rushed and forced. Maybe I should read the other finalists (if there is such a thing) to see which book lost out to this one!